While the jihadis of the Islamic State hope their reputation for brutality will deter their enemies, another group's snuff video shows that what has happened instead is an expansion of viciousness and cruelty.

CIA Director John Brennan said Sunday that Iran's involvement is complicating the US mission and may stir up sectarianism. Iraqi forces have surrounded Tikrit in preparation for a final push into the city.

Minority Yazidis were among those targeted by the self-proclaimed Islamic State during its expansion in northern Iraq and Syria. A UN panel accused the militants of committing genocide and crimes against humanity.